Method of plating nonmetallic surfaces



33% 19% D. c. GRESHAM 2533 454 METHOD OF PLATING NONMETALLIC SURFACES Fiied Sept. 8, 1945 10 NONMETALL/CSURFACE COATED WITH. WWTMLLYHYDR LWM' SHELL/3C 14 I FLA/N SHELL-AC 11mm BICHROMATE- I T JEMIT/ZEDSHELMC 10- RELIEF FORMED SILVER APFZ/FD 15 V 14 fi fi 515/45! Tl VE LA YE APPLIED REL IEF FORMED N A? N 1:11,/I/II/[IIIIIIIIIIIZIII/IIIII a l ETCHING 5/1. VE I? 17 V COLLOID ama? V////////////// SHELLAC Dom C. 1 i, r lwENToR BY Q 7 r ATTORE s Fatented Dec. 12, 1950 IVIETHOD OF PLATEN G NONMETALLIC SURFACES Donald Charles Gresham, Weaidstone, Harrow,

England, assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application September 8, 1945, Serial N 0. 615,244

In Great Britain October 4, 1944 3 Claims.

I This invention relates to the plating of nonmeta.lic surfaces.

Most non-metallic surfaces will not satisfactorily accept a plating layer such as silver, hence it is very difiicult to plate such surfaces with, for

. cesmstance, silver or copper.

According to the present invention We apply gzg fggggi l'flYggi'i to such a surface a layer of a partially hydro- Ammonia y l o lysed resln, such as part1a.ly hydrolysed shed-ac Distilled Water u 30 (see U. S. Patent 2,199,978), which is such that it can then be plated by chemical deposition of an electrical conducting substance such as silver.

According to the present invention there is provided the method of ohemcally depositing a lay of silver on a support w in there is first tangular sheet 8" x 6" can .be coated by Whirlapplied to the support a partially ydrolysed ing in a horizontal plane at 500 R. P. M. shellac on which silver can then be deposited. The coated material is thoroughly dried and Th omp y g r w n h w Sectional exposed behind a line negative of the design to views of the steps of e n a material accordbe silvered. This hardens the shellac where itv ing to my invention. is exposed, sufficiently to make it relatively in- The invention can be applied with advantage ol ble in commercial ethyl alcohol. to the forming of a design or image in metal, The t; operation is t dissolve t unhard such as silver by the following procedures! ened parts of the image away. This is done by.

(1) First form t e design image in Partially rocking the material bearing the shellac layerhydrolysed shellac and then deposit silver or the i t made from 1 gram of crystal i 1et i like chemically thereon. 1000 cos. of commercial ethyl alcohol. The aloof (2) First Protect a surface of Partially Y hol is repeatedly drained off the material until. lysed shellac where silver is not required so that th image is Seen t b l ar h al the lo se e unprotected parts form the desired desig dye solution is Washed off with a spray of water. or image and thereafter chemically d posit silso The material is next washed in four changes ver or the like on u unprotected areas. of distilled water and then silvered by rocking (3) First depos t S ve the like all 0V8! the it in the following mixture for five minutes: surface of some partially hydrolysed shellac and v there-after remove the silver where not required Solutwn A to form the design or image. silv nit t 30 grams One way of forming a photographic image by Distilled Water to 000 ccs. method (1) is to produce a relief image in the Add ammonia until precipitate formed t partially hydrolysed resin by making it light sendissolves sitive with bichromate and after exposure dissolving out unhardened parts with commercial ethyl alcohol, or by coating on it a bichromated Rochelle t, grams fish glue and after forming a relief image in the Water t 1 00 cc5 latter, the parts of the resin so laid bare are dissolved out with commercial ethyl alcohol. Solution c The hardened fish glue can then be removed for 4s Rochelle 11; 20 grams instance with a mixture of lactic acid and Water to 300 Water- Bring to boil, add 2.5 grams silver nitrate and The design 01' image formed. in any of the continue for minutesabove indicated ways can be thickened by elec- V tro-plating metal, such as copper or silver on it. so To .make the Sam mlxture take:

Example-Coat the material which is to form solutmn 10 Volsthe support for the silverecl design with a solution 9 Volsmade as follows: Solution C, 1 vol.

Make a Sto k solut o of 40 grams o d lac The material is finally washed in four changes resin having a softening point of C. to C. 55 of distilled water and dried,

} 2 and an acid value of 60 (sold by A. F.

Mix together:

To cos. of this mixtureadd 4 cos. of a 20%.

solution of ammonium bichromate in distilled water, shaking vigorously.

As a guide to the coating thickness, a fiat rec-.

Suter Com-. pany, London) which is a partially hydrolysed shellac in 100 cos. of commercial ethyl alcohol.-

Electrical resistances can be made by forming an image of the desired resistance in partially hydrolysed shellac (Process Engravers Cold Top Enamel) on an insulating material such as a phenol-formaldehyde resin impregnated cloth, silvering such image and then electroplating with copper.

My invention will now be described with reference to the accompanying drawing.

As shown therein, a non-metallic surface l may be treated in either of two ways by coating it with partially hydrolysed shellac. As shown in the left-hand side of the flow sheet, the partially hydrolysed shellac is bichromate-sensitized and coated as a layer I l on the non-metallic surface l0. A relief image is formed in the bichromate-sensitized shellac layer by exposure under an image and Washing out the unexposed portion of the layer to form relief image 12. Silver is then deposited on the relief image l2 as shown at I3, preferably by reducing a solution of silver nitrate to metallic silver in contact with the shellac relief image.

As shown at the right-hand side of the drawing, the partially hydrolysed shellac may be a plain shellac layer 14 and after coating on the non-metallic surface 19, a layer of silver 15 is applied to the shellac layer. A light-sensitive colloid layer I6 is then applied to the silver layer l and a relief image I! formed in the sensitive layer by exposure under an image and washing out the unexposed portions of the layer. The silver is then laid bare to leave silver image portions [8 beneath the colloid relief image portions ll.

The invention is useful in a large variety .of ways. For instance multicoloured designs may be produced with it. An example of such a design is as follows. This employs the'above mentioned Cold Top Enamel which is a substance which can be readily dyed. .A large selection of dyes exist which can be used since most ethyl alcohol soluble dyes are satisfactory, such as methyl violet and Sudan III. A line design in several colours is first drawn. A glass sheet is coated with a layer of Cold Top Enamel (partially hydrolysed shellac), hardened by exposure to light and silver is chemically-deposited on .it all over, for instance, using a mixture as given in the above example. This silvered surface is then coated with a layer of bichromated fish .glue and printed :under a colour separation positive of one of the colours of the said design. The unhardened fish glue is next washed out and the remainder is dried. The areas of silverso laid bare are then removed by treatment with an alcoholic etching solution, such as one of ferric nitrate. The Cold Top Enamel so laid bare is then dyed in a spiritwater solution of a dye. The enamel so dyed is then re-silvered. The'fish glue is next removed and then the plate is re-coated with a fresh layer of bichromated fish glue, and the sequence of operations repeated using a different dye. Such sequence can be 'repea'tedfor as many colours as required. Finally the whole of the silver can be removed leaving a multi-coloured design in the enamel, or if the silver is not removed then the plate forms a useful decorative imirror (viewed from the rear) with the design in colours on it.

Where we refer above to the use of fish glue for forming relief images, it is usually possible as an alternative to use other methods of forming relief images in a substance such as glue or gelatine, for instance, sensitive gelatino-silver halide emulsion can be used and an image formed therein by so-called tanning development or by tanning the gelatine by using a bichromate bleach bath for dissolving a silver image formed therein, or by etch-bleaching a silver image in gelatine.

What I claim is:

1. The method of forming a design or image in silver on a non-metallic surface, which comprises uniformly coating said surface with partially hydrolysed shellac having a softening point of C. to C. and an acid value of 60, and forming silver in image form on said shellac by reducing a solution of silver nitrate to metallic silver in contact with said shellac.

2. The method of forming a design or image in silver on a non-metallic surface, which comprises uniformly coating said surface with partially hydrolysed shellac having a softening point of 90 C. to 95 C. and an acid value of 69, applying a layer of silver to the shellac layer thus formed, by reducing a solution of silver nitrate to metallic silver in contact with said shellac layer, applying a light-sensitive colloid layer to said silver layer, forming a relief image in said light-sensitive col.oid layer by exposure to light and washing out unexposed portions of said layer and etching out the silver in the portions of the sensitive layer thus laid bare.

3. The method of forming a design or image in silver on a non-metallic surface, which comprises uniformly coating said surface with a bichromate-sensitized partially hydrolysed shellac having a softening point of 90 C. to 95 C. and an acid value of 60, forming arelicf image in said shellac layer by exposing a portion of said layer to light and washing out the unexposed portion of said layer, and then depositing silver on the residual portion of said shellac layer by reducing a solution of silver nitrate to metallic silver in contact with said shellac.

DONALD CHARLES GRESHAM.

REFERENCES CITED The following references are of record "in the file of this patent:

UNITED STATES PATENTS 

1. THE METHOD OF FORMING A DESIGN OR IMAGE IN SILVER ON A NON-METALLIC SURFACE, WHICH COMPRISES UNIFORMLY COATING SAID SURFACE WITH PARTIALLY BYDROLSED SHELLAC HAVING A SOFTENING POINT OF 90*C. TO 95 DEGREES C. AND AN ACID VALUE OF 60, AND FORM 